1. Field of the Invention
The present invention relates generally to solar battery systems for vehicles, and more particularly, to a system for supplying electrical equipment of a vehicle with electric power produced by a solar battery, in which the solar battery is mounted on a vehicle body and the function of the solar battery as a power source is monitored in the cabin of the vehicle.
2. Description of the Prior Art
When a vehicle with a closed cabin, such as a passenger car, is parked for hours to be exposed to the scorching heat of the sun, the temperature in the cabin may be extremely increased compared with the atmospheric temperature outside of the vehicle. In a condition in which the temperature in the cabin has risen to be so high, a driver or passenger getting in the vehicle feels uncomfortable and it takes a long time to reduce the temperature in the cabin to be agreeable after an air conditioner of the vehicle is started to operate.
For the purpose of relieving such inconveniences, there has been proposed to provide a vehicle with a ventilation arrangement which includes ventilation ducts formed in a vehicle body to cause the cabin of the vehicle body to communicate with the outside of the vehicle and ventilating fans disposed in the ventilation ducts, respectively, wherein each ventilating fan is caused to operate for exhausting air from within the cabin to the outside of the vehicle and taking fresh air into the cabin. The effect is to reduce the temperature in the cabin when a difference between the temperature in the cabin and the atmospheric temperature outside of the vehicle reaches a predetermined value. In such a ventilation arrangement, however, since the ventilating fans are usually driven by electric power supplied from a storage battery employed in the vehicle, it is feared that the storage battery is subject to an excessive load to drive the ventilating fans in a parked vehicle without being charged.
Accordingly, it has been also proposed to use, in place of a storage battery, a solar battery which is operative to directly convert solar energy to electric energy in order to supply electric power for driving ventilating fans provided in such a ventilation arrangement as mentioned above, as disclosed in, for example, the Japanese examined patent specification No. 59-51451. In this case, the solar battery is mounted on a roof of a vehicle body to have a plurality of light receiving areas covered by a glass plate and facing upward to the outside of the vehicle body so as to receive the sunlight effectively, wherein the electric power obtained i response to the quantity of solar radiation from the solar battery is applied to each of the ventilating fans to drive the same.
In the case of the solar battery, when the light receiving areas cannot receive the sunlight properly due to some shading substance attached to the glass plate covering the light receiving areas or breakages of the glass plate, or the light receiving areas get out of order substantially, the solar battery malfunctions so as not to properly produce electric power in response to the quantity of the solar radiation. If the malfunction of the solar battery is not detected by the driver or passenger and the malfunctioning solar battery continues to apply electric power to each of the ventilating fans to drive the same, the solar battery is not used effectively or is unable to supply the electric power required for driving the ventilating fans. In a situation wherein the malfunctioning solar battery is used as a power source for the ventilating fans without being noticed by the driver or passenger, as mentioned above, the result is either that the ventilation arrangement cannot operate effectively, or the storage battery provided in addition to the solar battery needs to continue supplying the ventilating fans with sufficient electric power for driving the same, and thereby is subjected to the danger of excessive discharge.